Dynamic evolution from positive to negative magnetoresistance of RAlGe (R = Dy, Ho) with disordered orthorhombic structure

The single-phase disordered alloys of RAlGe (R = Dy, Ho) are successfully prepared by arc-melting, and their structures and physical properties are investigated by X-ray diffraction, magnetization, specific heat, electric transport and magnetoresistance measurements. RAlGe crystallizes into an orthorhombic YAlGe-type structure with a space group of Cmcm, and three kinds of crystal positions are randomly occupied by (Al, Ge) at 4a (0, 0, 0) site, (R, Al) at 4c (0, 0.31, 0.25) site, and (Ge, R) at 4c (0, 0.61, 0.25) site, respectively. RAlGe exhibits strong relation effect among magnetic and electric as well as thermal properties, it shows that the magnetic, thermal and electric phase transitions simultaneously occur. The thermal and electric phase transitions are associated with the magnetic transition. The magnetoresistance shows the dynamic evolution from positive to negative with increasing temperature from the magnetic transition temperature Tt to Neel temperature TN. It is suggested to be due to the temperature induced magnetic phase transition from AFM-I to AFM-II, which causes the decrease of spin disordered scattering. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The single-phase disordered alloys of RAlGe (R = Dy, Ho) were prepared and their structures and physical properties were investigated. The materials showed strong correlation effects among magnetic, thermal, and electric properties, with simultaneous phase transitions occurring in all three areas. The magnetoresistance also exhibited temperature-dependent changes, possibly related to the temperature-induced magnetic phase transition.